1. If you use the current (5.0.7 and later) connector with Tiger, it will revert to using Sync Services and not allow the CalDAV option.

2. I used to get it predictable by making sure that both Zimbra has the contacts and calendars perfect, then use the connector to overwrite the Mac with the Zimbra server-side contents. If you also have Entourage in the mix, you will have conflicts pop-up--disable that if you can.

3. This has not been a problem for me with Tiger or Leopard in a long time-- see my solution for number 1 for settling that down.

4. In getting an event in Mail as an ics file you can open in iCal and accept it there, though I think the Zimbra Web Client is better for this kind of thing.